public class UserClient {
    public static void main(String[] args) {
        UserControllerObservable observable = new UserControllerObservable();
        //添加观察者MailObserver
        observable.addObserver(new MailObserver());
        //添加观察者MessageObserver
        observable.addObserver(new MessageObserver());
        //用户功能
        observable.register("张三","123");
        observable.register("李四","123");
        observable.register("王五","123");
    }
}